Hi
By September 2010 I will be in the State on F1 for 5 years. So I think I should be considered resident Alien (for tax purpose). However, I will always fail the resident alien test because none of the days as F1 counts.
I want to buy a house before April 1st this year, and I know only resident aliens are eligible for the $8000 credit. So I am wondering whether I can be considered a resident alien when I file the 2010 tax return in 2011, and take advantage of the tax credit. Should I file 1040NR-EZ or 1040-EZ then? Thanks so much.

When did you enter the U.S.

September, 2005

You are nonresident for years 2005 to 2009. You will be resident in 2010. So you can claim homebuyer credit on your 2010 tax return.
For qualifying purchases in 2010, taxpayers have the option of claiming the credit on either their 2009 or 2010 return.
Your U.S. Tax Return: First-Time Homebuyer Credit

Thanks MukatA! That's so helpful. So if I am resident Alien, I file 1040EZ.
And if I am non-resident alien, I file 1040NR-EZ, right? Or can I choose to file either 1040EZ or 1040NR as a non-resident alien? (cause the 1040 has more benefits than 1040NR this year). Thanks again!!

If you claim the $8,000 First Time home Buyer's Credit on your 2010 return, you must file Form 1040 with Form 5405.

Note that the house MUST be purchased in 2010 to qualify.